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isolated ground for single outlet on dedicated circuit: re..

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Anonymous
March 21, 2005 4:01:06 PM

Archived from groups: rec.audio.pro (More info?)

If I have a dedicated AC circuit run for my audio system, but there's
only one outlet on that circuit, is there any point in making that an
Isolated Ground circuit?

IOW, I'm presuming by being on a separate circuit from the others in
the house the audio system is not sharing a common ground with, say,
the refridgerator. Is this correct?

And if there aren't any other AC outlets on that dedicated audio
circuit, I don't need to worry about isolating that outlet's ground
from any other outlets in the room, right?

Do I understand the concept correctly, or have I missed something?

Thanks.
Anonymous
March 21, 2005 8:56:21 PM

Archived from groups: rec.audio.pro (More info?)

Buster Mudd <mr_furious@mail.com> wrote:
> If I have a dedicated AC circuit run for my audio system, but there's
>only one outlet on that circuit, is there any point in making that an
>Isolated Ground circuit?

It is by definition an isolated ground circuit already. So you might as
well put the orange receptable in.

>IOW, I'm presuming by being on a separate circuit from the others in
>the house the audio system is not sharing a common ground with, say,
>the refridgerator. Is this correct?

Well, it is once it gets to the panel, but there's nothing you can do
about that short of having a seperate service entirely (which some studios
do).

>And if there aren't any other AC outlets on that dedicated audio
>circuit, I don't need to worry about isolating that outlet's ground
>from any other outlets in the room, right?

Right.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
March 21, 2005 8:59:27 PM

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey <kludge@panix.com> wrote:
>Buster Mudd <mr_furious@mail.com> wrote:
>> If I have a dedicated AC circuit run for my audio system, but there's
>>only one outlet on that circuit, is there any point in making that an
>>Isolated Ground circuit?
>
>It is by definition an isolated ground circuit already. So you might as
>well put the orange receptable in.

(err... that should be receptacle).

I am assuming insulated-jacket cable here by the way, like Romex or plastic
conduit. When you're running in conduit or running BX, it is important to
keep it electrically isolated throughout the run. But for typical home
construction with Romex junk, that's a non-issue.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Anonymous
March 22, 2005 12:35:40 AM

Archived from groups: rec.audio.pro (More info?)

You cannot isolate the Ground pole as it a common and its integrity
throughout the building is (should be) verifiable by low resistance (below
0.3 ohm) all the way to the street cable.
You can try to "clean up" your mains with surge and spike protectors, but
it's the devices that produce AC interference, ie, boilers, fridges,
freezers, by intermittent use, lift/elevator motors being the worst, that
should be suppressed at source.
Anonymous
March 22, 2005 12:43:59 AM

Archived from groups: rec.audio.pro (More info?)

On 21 Mar 2005 13:01:06 -0800, "Buster Mudd" <mr_furious@mail.com>
wrote:

> If I have a dedicated AC circuit run for my audio system, but there's
>only one outlet on that circuit, is there any point in making that an
>Isolated Ground circuit?
>
>IOW, I'm presuming by being on a separate circuit from the others in
>the house the audio system is not sharing a common ground with, say,
>the refridgerator. Is this correct?
>
>And if there aren't any other AC outlets on that dedicated audio
>circuit, I don't need to worry about isolating that outlet's ground
>from any other outlets in the room, right?
>
>Do I understand the concept correctly, or have I missed something?
>
>Thanks.
IG also means that an insulated ground wire is supposed to be run back
to the buildings (single point of) ground buss. Please do not confuse
Ground with Neutral (which happens to be at ground in the USA).

Metal conduit, boxes contacting OTHER grounded points in a structure
can result in ground currents via the conduit.
*If* lightning should strike nearby (no necessarily the structure)
HUGE currents can flow via these paths and the effect on equipment can
be devastating.

I did some tests on telephone equipment in a tall building in Chicago
that had a satellite link on the roof. There was a #2 bare bond wire
between the basement telco switch and the rooftop equipment. About 6
amps of current was flowing UP from the basement. About 5 amps was
flowing DOWN from the roof. Technically, there should have bee NO
current flowing as this was a chassis bond, not part of power or
signal. My first recommendation was replace the wire wit INSULATED to
eliminate mid run ground contact.

, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org
Anonymous
March 22, 2005 12:20:55 PM

Archived from groups: rec.audio.pro (More info?)

On Mon, 21 Mar 2005 16:01:06 -0500, Buster Mudd wrote
(in article <1111438866.316388.132730@z14g2000cwz.googlegroups.com>):

> If I have a dedicated AC circuit run for my audio system, but there's
> only one outlet on that circuit, is there any point in making that an
> Isolated Ground circuit?

my guess is no, if the power and grounds both run back to the panel.


> IOW, I'm presuming by being on a separate circuit from the others in
> the house the audio system is not sharing a common ground with, say,
> the refridgerator. Is this correct?

hmm, good question. I have heard people talk about noise working it's way
through a ground system. The circuits all become common at the buss bar in
the power panel. How much noise could leak from one branch through the box
and back out is a question I can't answer.

Ground loops caused by current passage across small resistive differences
between outlets and among branches, however, are eliminated by keeping
everything on one outlet.

> And if there aren't any other AC outlets on that dedicated audio
> circuit, I don't need to worry about isolating that outlet's ground
> from any other outlets in the room, right?

You should have a separate ground for that outlet. Since it's a dedicated
line, I'm presuming the ground also goes all the way back the the box and
doesn't connect to any other grounds. That's what it should do. Connecting
to any other ground is opening the door for problems.

> Do I understand the concept correctly, or have I missed something?
>
> Thanks.
>

Nobody's perfect.

Regards,

Ty Ford


-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com
Anonymous
March 22, 2005 8:59:09 PM

Archived from groups: rec.audio.pro (More info?)

Ty Ford <tyreeford@comcast.net> wrote:

>> And if there aren't any other AC outlets on that dedicated audio
>> circuit, I don't need to worry about isolating that outlet's ground
>> from any other outlets in the room, right?

> You should have a separate ground for that outlet. Since it's a dedicated
> line, I'm presuming the ground also goes all the way back the the box and
> doesn't connect to any other grounds. That's what it should do. Connecting
> to any other ground is opening the door for problems.

I think you want to make sure that the wiring feeding this receptacle
isn't two circuits with a shared ground, which I think is pretty
common and the wiring is something like Romex 14/3. I know
you are covering that Ty, but it might not be obvious.

Rob R.
Anonymous
March 23, 2005 12:47:45 PM

Archived from groups: rec.audio.pro (More info?)

On Tue, 22 Mar 2005 12:59:09 -0500, Rob Reedijk wrote
(in article <d1pmdd$san$1@news1.chem.utoronto.ca>):

> Ty Ford <tyreeford@comcast.net> wrote:
>
>>> And if there aren't any other AC outlets on that dedicated audio
>>> circuit, I don't need to worry about isolating that outlet's ground
>>> from any other outlets in the room, right?
>
>> You should have a separate ground for that outlet. Since it's a dedicated
>> line, I'm presuming the ground also goes all the way back the the box and
>> doesn't connect to any other grounds. That's what it should do. Connecting
>> to any other ground is opening the door for problems.
>
> I think you want to make sure that the wiring feeding this receptacle
> isn't two circuits with a shared ground, which I think is pretty
> common and the wiring is something like Romex 14/3. I know
> you are covering that Ty, but it might not be obvious.
>
> Rob R.

Persactly.

Ty Ford



-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com
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